Condensed Consolidated Financial Statements - Recent Accounting Pronouncements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Recent Accounting Pronouncements
Long-term deferred income taxes payable	$ 581,203		$ 565,404
Diluted earnings per-share (in dollars per share)	$ 0.65	$ 0.52
Adjustment | Accounting Standards Update 2015-17
Recent Accounting Pronouncements
Deferred tax assets, current			(129,300)
Long-term deferred income taxes payable			$ (129,300)
Scenario, adjustment | Accounting Standards Update 2016-09
Recent Accounting Pronouncements
Income tax benefit	$ 3,000
Diluted earnings per-share (in dollars per share)	$ 0.05